Plug-in panel unit



2 Sheets-Sheet 1 INVENTOR.

June 2, 1964 H. J. HAMMERLY PLUG-IN PANEL UNIT Filed Nov. 7, 1961 #ERNAN J HAMMER 4 77'aRA EY 2o I I3;

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} MAJ l June 2, 1964 H. J. HAMMERLY PLUG-IN PANEL UNIT 2 Sheets-Sheet 2 Filed Nov. 7, 1961 INVENTOR. F 6 745m w /W gmj y 4 from/5 Y 3,135,395 PLUG-IN PANEL UNKT Herman J. Hammeriy, Piaiuviiie, Conn, assignor to General Electric Company, a corporation of New York Filed Nov. 7, 1961, Ser. No. 150,831 2 Claims. (31.317-116) My invention relates to electrical control panel units and particularly to such panel units of the plug-in type.

Control panels for electric circuit breakers of the plugin type, such as shown for example in Patent No. 2,738,446, Fleming, assigned to the same assignee as the present invention, have found Wide acceptance throughout the electrical industry for use in mounting and connecting electrical protective devices of the circuit breaker type. The great convenience and ready acceptance of this type of panel has led to a demand for comparable assemblies-for fusible equipment. The dimensions of the standard plug fuse, that is, thetype of fuse having a screw-threaded base for mounting in a standard Edison socket, however, are such that a plug-in unit including such fuses cannot be mounted in the same modular space as occupied by a standard plug-in circuit breaker of comparable rating.

Thus for example, the center-to-center spacing of plugin contacts on a standard plug-in circuit breaker panel, is one inch. Accordingly, the overall width-wise dimension of a plug-in circuit breaker for use in such a panel is slightly less than one inch for each'such single-pole circuit breakeror for each pole of a multi-pole circuitbreaker. The diameter of a standard plug type fuse, however, is slightly more than 1%" at the top, the socket itself being one-inch in diameter, without allowance for insulation.

As a result, panels which have been provided heretofore to accept plug-in fusible units, have included stationary contacts of greater spacing than those on corresponding circuit breaker plug-in panels. A separate line of panels has therefore been required for such fusible units, and such units cannot be exchanged for plug-in circuit breaker units in equipment already in use.

It is an object of the present invention to provide a ping-in fusible unit which is usable in a panel having stationary contact spacings suitable for receiving standard plug-in type circuit breakers.

It is another object of the invention to provide a plugin fusible unit which has mounting and retaining means identical to that of existing standard circuit breakers.

It is another object of the invention to provide a plugin fusible unit which provides the maximum number of fused circuits within a given space in a plug-in panel.

It is a further object of the invention to provide plugin fusible units which when used on a conventional plugin type panel will maintain a balanced load distribution on the panel busbars. 1

In accordance with the invention, I provide a plug-in fusible unit for use in plug-in type panels of standard dimensions, each unit including three standard plug-type fuses in oifset arrangement within an insulating body which occupies the same lateral dimension as two standard plug-in type circuit breakers. The three fuse sockets are connected to two plug-type connectors adapted to contact the stationary contacts of a plug-in type panel. The arrangement, moreover, is such that when a pair of plug-in fusible units of the invention are mounted in end-to-end relation on a plug-in type panel, they provide six plug-type fuse sockets which occupy the same panel space as taken by four standard plug-in type circuit breakers. Moreover the six fuse sockets are equally divided between the two stationary panel contacts, there being three connected to each such contact.

The invention will be more fully understood from the I 3,135,895 Patented June 2, 1964 lCC following detailed description and its scope will be pointe out inthe appended claims.

In the drawings,

FIGURE 1 is a plan view of an electrical control panel including plug-in control units in accordance with the invention, the outer metallic box or enclosure for the panel being omitted;

FIGURE 2 is a schematic diagram of a plug-in fusible unit in accordance with the invention;

FIGURE 3 is a schematic drawing showing the connections of two plugin fusible units when in mounted condition;

FIGURE 4 is a back view of a plug-in fusible unit of the invention; 7 I

FIGURE 5 is an exploded perspective view showing the connecting straps and terminals of the plug-in fusible unit of FIGURE 3;

FIGURE 6 is a schematic drawing showing the connections of another embodiment of the invention. 7 e

In the drawings, the invention is shown in FIGURE 1 as incorporated in a panel assembly comprisinga generally channel-shaped supporting pan or base 10 having a pair of busbars 11a and 11b supported at their opposite ends by insulating blocks 12 and 13 respectively. Each of the busbars 11a and 111) has a plurality of integral offset upstanding contact blades 14a and 14b and each is provided with a terminal cable connector 29 and 21 respectively. Intermediate portions of the busbars 11a and 1112 are covered by insulating shields 15. The insulating block 12 is held in place by lugs 16 struck up from the back wall of the channel Iii, and the block 13 is 1 held in place by screw 17.

The base 10 includes a pair of outwardly extending horizontal flange portions 18, each having a row of integral hook-shaped lugs 19 struck up therefrom for a purpose to be described.

The supporting pan 10 and contact blades 14a and 14!) are adapted to receive standard plug-in type circuit breakers such for example as the type shown in the abovementioned patent. In accordance with this construction, each of the circuitbreakers 22 includes an integral lug portion, not shown, at one end, and a pair of contact jaws at the other end. In use, the circuit breaker is mounted by hooking the lug portion thereof under one of the hooks 19 and rotating the breaker about the hook 19 into plug-in engagement with the corresponding contact blade 1411 or 1419. The circuit breakers whenrnounted occupy a position as shown in FIGURE 1 in which one end rests on the flange 18, held by the hook 1 9, and the other end frictionally engages a contact blade 14a or 14b.

The contact blades 14a and 1412 are spaced apart a distance x equal to the width of a single pole circuit breaker 22, so as to mount such breakers in compact fashion and also so as to be able to receive two and three pole circuit breakers having their contact jaws spaced therein a distance x apart.

In accordance with the invention, Lprovide plug-in fusible units 24, having a width dimension equal to 2x or double the width dimension of a single pole circuit breaker, and having contact jaws spaced thereon a distance x equal to the spacing of the contact blades 14a, 14b.

Each of the plug-inunits 24comprises a generally rectangular insulating block 26 having three cylindrical recesses 25 extending therein from thefront thereof, and containing the three screw-type fuse shells 27, 28, and 29. Each of the fuse shells 27, 28, and 29 has a corresponding centrally positioned stationary central contact 30, 31 and 32. A pair of plug-in type contact sockets 33 and 34 are positioned adjacent the end wall and back wall of the body 24 to make plug-in connection with the contact blades 14a and 14b. At the other end of the insulatmg body 26, three wire connecting terminals 35, 36 and 37 are provided. A pair of connecting straps 38 and 39 are provided for connecting the sockets 33 and 34 to the center contacts 30, 32 and 31 respectively. The strap 38 connects the socket 33 to the center contacts 39 and 32, while the strap 39 connects the socket 34 to the center contact 31. The fuse shell contacts 27, 28 and 29, in turn, are connected to the wire connector terminals 35, 37 and 36, by connecting straps 40, 41 and 42 respectively.

The assembly of each of the fuse shells is as illustrated in FIGURE 5, in connection with the fuse shell 29. Thus the center contact 32 is in the form of a headed bolt which passes through an insulating washer 43, through a clearance hole 44 in a jumper strap 45, through a clearance hole 29a in the fuse shell 29 and then threads into a hole at the end of the conductor strap 38. Tightening the stud 32 therefore clamps the jumper strap 45 against the bottom wall of the fuse shell 29, and also clamps the strap 45 and the shell 29 against the bottom wall of the insulating body 26. It also holds the strap 38 in place on the insulating body 26.

The jumper strap 45 is connected to the conductor 42 by means of .a screw 46 which is inserted from the back of the assembly. The screw 46 passes through the bottom wall of the insulating block 26, through a clearance hole in the conductor 42 and into threaded engagement in the opening 45a of the jumper strap 45.

Thus the current path through this fuse socket is as follows: from the socket 33, to the conductor 38, to the stud 32, through a fuse, not shown, to the fuse shell 29, to the jumper strap 45, to the conductor 42, and finally to the wire connector 36. In a similar manner, the current path through the fuse mounted in the fuse shell 27 is as follows: from the socket 33 to the conductor 38, to the contact stud 30 through a fuse, not shown, to the fuse shell 27, to the conductor 40, to the wire connector 35. Also, the current path through the fuse mounted in the fuse shell 28 is as follows: from the socket 34 to the conductor 39 to the center contact stud 31 through a fuse, not shown, to the fuse shell 28 to the conductor 41, to the wire connector 37. The schematic diagram of these electrical connections is as shown in FIGURE 2.

In a similar manner, the fuse shells 28 and 27 are connected by screws 47 and 48 to the straps 41 and 40 respectively. The connector straps 40, 41 and 42, which connect the fuse shells to the wire connector terminals 35, 37, and 36 respectively, are held in place at one end by the screws 46, 47, 48. The other end of the straps 40, 41, and 42 is supported on insulating shelf portions of the insulating body 26 comprising insulating barriers 50 and 51.

The strap 38 is held in place by the contact studs 36 and 32, associated with the fuse shells 27 and 29 respectively. The strap 39 is held in place by the contact stud 31 and also by screw 39A, inserted from the back, through a clearance hole 39B, into threaded engagement with the base 26.

It will be observed that the wire connecting terminals 35, 36 are both fed from the same line contact, i.e., contact 33. These terminals are therefore at the same electrical potential. The third wire connecting terminal 37, is fed from the other line contact 34, and therefore would ordinarily be at a different potential from the other two wire connectors when used. In order to isolate the wire connector 37 from the connectors 35 and 36, I provide a barrier 52 parallel to the side walls of the body 26 and having a slot 53 cut therein to provide a long over-surface electrical clearance path between the wire connectors 36 and 37 (see FIGURE 4). The Wire connectors 35 and 37 are further protected by extensions 54 and 55 of the side walls of the insulating body 26. The barrier 50 extends transversely between the barriers 52 and 54, and the barrier 51 extends transversely between the barriers 52 and 55, and provide a shelf supporting the ends of the conductor straps 40, 41, 42.

As shown in FIGURE 1, the single pole circuit breakers 22 have width dimension x, and the stationary contact blades 14a, 14b are therefore spaced apart a distance x. The insulating block 26 in accordance with the invention has a width dimension of 2x equal to twice the width of a single pole circuit breaker. The unit 24 therefore plugs onto two adjacent contact blades 14a, 14b as shown in FIGURE 1.

The unit 24 also includes a bridging piece 56 extending transversely across the bottom wall thereof and held in place by a non-removable screw 57. The bridging member 56, has a portion 58 which acts as a mounting lug to be received under one of the retaining lugs or hooks 19 on the flange 18 to retain the unit in mounted position. The portion 58 comprises a metallic lug which is trapped in place between the bridging piece 56 and the main body of the insulating block 26.

It will therefore be observed that one of the plug-in fusible units 24 may be mounted on a conventional panel base as shown, occupying a vertical space equal to that taken by two single pole circuit breakers. Thus three fuse-circuits are provided in accordance with the invention in the same effective space as required for only two circuit breakers. Thus it is not only possible to mount a plug-in fusible unit in the same panel as circuit breakers, but the total capacity of the panel is increased by one third when the plug-in fusible units are used.

The plug-in fusible units 24 are preferably mounted in end-to-end relation, each contacting one half of the same two contact blades 14a, 14b. As shown in FIG- URE 3, each contact blade therefore has connected to it three fused circuits, thus maintaining a dseirable equal balance of the electrical load between the two main busbars 11a and 11b.

In the form of the invention shown schematically in FIGURE 6, one of the fuse sockets, i.e., socket 28 and its associated connections, including line terminal 34, conductor 39, conductor 41 and wire connector 37 are omitted, and only the fuse sockets 27 and 29, connected to the line terminal 33 are used.

It will be observed that in this form, as in the previous form, the loading is maintained in balanced condition when such units are mounted in end-to-end relation, since the total load of four circuits is divided equally between two contact blades.

The units shown in FIGURE 6 are also preferably made with a lateral dimension of 2x, where x is the centerto-center spacing of the stationary contact blades. The positioning of the line terminal 33 is the same as in the previous form, i.e., off-center with respect to the insulating body, so that when mounted, the units contact two adjacent contact blades and occupy exactly the same space as taken by four single-pole circuit breakers having a lateral dimension x, and provide four fused circuits therein.

It will be seen that there is provided in accordance with the invention a plug-in fusible panel unit which may be used interchangeably with plug-in circuit breaker units of standard dimensions, thereby providing panel assemblies of great versatility.

While the invention has been illustrated in only one embodiment, it will be readily apparent that many modifications thereof may be made, and I therefore intend by the appended claims to cover all such modifications as fall within the true spirit and scope of the invention.

What I claim as new and desire to secure by Letters 'Patent of the United States is:

1. A fusible panel unit comprising a generally rectangular insulating body having opposed front and back walls opposed end walls and opposed side walls, three sockets carried by said insulating body for mounting and connecting electric fuse devices having a generally cylindrical body portion, two line terminal connectors adjacent one of said end walls of said body, means connecting one of said line terminals to two of said fuse sockets, means connecting the other of said line terminals to the other of said fuse sockets, three load terminal connectors adjacent the other of said end Walls of said body, means connecting each of said fuse sockets to one of said load terminal connectors, said fuse sockets each having a dimension measured in a direction perpendicular to said side Walls equal to at least one-half the distance between said side walls and being offset with respect to said end Walls to fit between said side Walls, said fuse sockets each having a dimension measured in a direction perpendicular to said end walls equal to at least one third the distance between said endwalls, and being offset with respect to said side Walls to fit between said end Walls, said line terminal connectors being spaced apart a distance sub- 6 stantialiy equal to one-half the total distance between said side walls of said body.

2. A fusible panel unit as set forth in claiml, said line terminal connectors also being spaced equally from and on opposite sides of a plane passing through said body parallel to and mid-Way between said side Walls.

References Cited in the file of this patent UNITED STATES PATENTS 

1. A FUSIBLE PANEL UNIT COMPRISING A GENERALLY RECTANGULAR INSULATING BODY HAVING OPPOSED FRONT AND BACK WALLS OPPOSED END WALLS AND OPPOSED SIDE WALLS, THREE SOCKETS CARRIED BY SAID INSULATING BODY FOR MOUNTING AND CONNECTING ELECTRIC FUSE DEVICES HAVING A GENERALLY CYLINDRICAL BODY PORTION, TWO LINE TERMINAL CONNECTORS ADJACENT ONE OF SAID END WALLS OF SAID BODY, MEANS CONNECTING ONE OF SAID LINE TERMINALS TO TWO OF SAID FUSE SOCKETS, MEANS CONNECTING THE OTHER OF SAID LINE TERMINALS TO THE OTHER OF SAID FUSE SOCKETS, THREE LOAD TERMINAL CONNECTORS ADJACENT THE OTHER OF SAID END WALLS OF SAID BODY, MEANS CONNECTING EACH OF SAID FUSE SOCKETS TO ONE OF SAID LOAD TERMINAL CONNECTORS, SAID FUSE SOCKETS EACH HAVING A DIMENSION MEASURED IN A DIRECTION PERPENDICULAR TO SAID SIDE WALLS EQUAL TO AT LEAST ONE-HALF THE DISTANCE BETWEEN SAID SIDE WALLS AND BEING OFFSET WITH RESPECT TO SAID END WALLS TO FIT BETWEEN SAID SIDE WALLS, SAID FUSE SOCKETS EACH HAVING A DIMENSION MEASURED IN A DIRECTION PERPENDICULAR TO SAID END WALLS EQUAL TO AT LEAST ONE THIRD THE DISTANCE BETWEEN SAID END WALLS, AND BEING OFFSET WITH RESPECT TO SAID SIDE WALLS TO FIT BETWEEN SAID END WALLS, SAID LINE TERMINAL CONNECTORS BEING SPACED APART A DISTANCE SUBSTANTIALLY EQUAL TO ONE-HALF THE TOTAL DISTANCE BETWEEN SAID SIDE WALLS OF SAID BODY. 